Develop Reference

IntelliJ strange behavior

I've installed 30 day trial of IntelliJ 15.0.2 and cloned my project using git (I've created this project in community version). Project compiles (maven), runs, works. But new IntelliJ does not underline my errors, misspellings etc. When I wanted to commit, IntelliJ shows big number of errors, mostly on imports, as it can't resolve them. All dependencies are inside pom.xml. Once again, there were no errors in community version of IntelliJ. Ultimate version builds project just fine, but doesn't underline any errors and shows almost every import as unsolvable. What could go wrong? How to fix it?

Go to Build -> Make Project. After that errors should be visible in the project tree and in the specific project files.

You may need to mark the source dir, by right-clicking it on the project tab and select mark directory as -> source root

Check that you have a correct project sdk set in modules configuration. If IJ doesn't found any classes, jdk classes included, probably there is no sdk set.
You can also try to invalidate caches (in File menu) and rebuild project

I have faced with strange behaviour of Intelij Idea after update (syntax highlight stopped working). If you want to understand what is going on with yor Idea and can not quickly find an answer in internet, just go to Log files (for Mac OS the path is
~/Library/Logs/IntelliJIdea< your version>
List all files in that directory
ls -la
in terminal and find the latest one. Usually it should be idea.log (without numbers, logs with numbers identify logs for previous days). View that log. If that log contains a lot of ERRORS, try to find the reason (you can just type
grep "ERROR" idea.log
in terminal to find all lines that contain errors). Usually log files shouldn't contain errors, just info and warnings.
In my case syntax highlight stopped working. The log looked like
You can see here that error is in plugins that called like haxe.
I found that plugin in my idea, uninstalled it and idea started working properly. I investigated the log after and what I have seen there:
You can see just INFO in new rows.
Investigating a log can be really useful if you can not find the rootcase of your problem quickly in the internet. I hope it can help you even if it can be quite tricky.
Good luck!

Java/Eclipse - No more R file ever

I'm on Eclipse for hours now and I didn't found a solution yet for my problem even after many searches on internet: I have no more R.java file on my projects.
On just created or on my old projects, i don't have R file anymore and I tried so many solutions (uninstall, re-install Eclipse, clean my project, check all my XMLs, fix problem with android tool and so on ...)
Please someone can tell me what to do in this case?

Hey If you just updated to ADT Rev 22 :
I had the problem too. There is a new component in the Tools folder called "Android SDK Build-tools" that needs to be installed.
Step 1
Open the Android SDK Manager
Step 2
Select the newly added Build Tools and install. (If problem stays then go to Project Properties => Java Build Path => Order and Export and check Android Private Libraries, then clean and build project.
It may be necessary to repeat the process, restart the SDK Manager after the update and make sure it looks like this (all tools installed):
More info:https://groups.google.com/forum/?fromgroups=#!topic/android-developers/rCaeT3qckoE%5B1-25-false%5D

Perhaps in Project Properties -> Java Build Path -> Libraries you don't have:
Android 4.2.2 (or other version)
Android Dependencies ?
If so, then right click project - > Android tools -> fix android properties
and see if this library showed up.

Thank you all for saving me! I've spent the whole afternoon on search this error.
Finally, my project works.
By the way, I also encountered one problem which i wanna share with you:
After upgrading, even if my project has not errors anymore. During runtime, it seems it couldn't find the classes from the jars placed in \libs.
Go into Project=>properties => Java build path= > Order and Export.
Please make sure all your jars are checked.

If this problem occurs suddenly in a well working project,
the first step is to find whether the problem occurs only in the current project or in all other projects.
if all other projects in the current workspace are working then 90% problem is with XML / mainfestfile/resourse file that you edited recently.
This error is not shown as red mark we have to find out what we have done recently in these files.

try this
sudo apt-get install lib32stdc++6 lib32z1 lib32z1-dev
it solved my problem

Close your eclipse and after refreshing system, try to open Eclipse again. I think you are using Emulator along with the eclipse. It may be because of the low Memory problem (RAM) of your system. I used to face the same problem when I use Emulator

whenever there is any mistakes in any of the xmls the R goes missing when a build or clean happens so check for any xml errors in your project unless you fix it you cant get back your R on clean or build. fix the xml files and perform a clean you will have the R generated. Also check in File->properties->Builders and see if everything is checked

I was using Eclipse Indigo and nothing I tried worked. I ended up downloading Juno SR2, reinstalling the ADT, and now everything works again.

Reinstall everything and it'll work.. i.e. go back to Google SDK or w.e. you're using and download it.
Update it to latest in SDK Manager.
Go into Eclipse-Project-Prefs-Java build path-order/export TICK EVERYTHING.

problem: No R file get generated.
guess: Try cleaning project if it is old one. Else create new project with no R get generated and with no compile errors but this: no project.apk
In this case you have to check your SDK for the built-tools. May not be installed after updating SDK.
Thus download them if not download here, then put them under directory: SDK/built-tools folder. Lastly, and most important, is to Run the SDK As Administrator. This guarantees refreshing SDK with all packages appearing in it.
Install the SDK-Built-Tools or any missing packages according to the above link and you're done.
hope this helps.

Try one thing, create a new Android Project and transfer all those files which are in the previous project. That worked for me.

In my case there is error due to "&" inside strings.xml file(but error not shown) for declaring string for a array type. Now the problem has been solved as I changed "&" to "and".
So, please make sure that you do not have such silly use of symbols, and clean the project.

I have had the same kind of problem, however Rechecking all XML files in the Resources folder was helpful in my case. I found syntax error in my XML files. Cleaning and building the project again can be helpful sometimes too.

I had the dreaded not more R.java.
Some of the things I've used in the past:
Clean / rebuild (the first thing we all try)
Restart eclipse (optionally reboot pc/mac)
Update both SDK/ADT eclipse plugin to latest version
Create new eclipse workspace and import project
Enable Verbose AAPT build output Eclipse menu>Preferences>Android>Build
Port project to Android Studio / Gradle (this helped my actually see the AAPT error i was getting Error Code:138)
Delete recent XML changes - Ultimately I found deleting recent menu.xml files I'd added and commenting out where they were referenced fixed the issue and I finally got R.java.

I got the error recently and had found no fault in any layout or value file. After a lot of tries I add another Activity and the R.java was build and the error disappeared. I don't know why this occur, but it takes me hours.

Grails projects often become unconfigured in eclipse after I restart my machine

I have little experience in Java/Groovy/Grails, about 1 year using Eclipse and some weeks using GGTS, and I always got my projects with build path problems, or other related problems, with apparently no reason. The environment seems to be buggy. Any tip?
Below there's an screenshot of a project I was working on and, after a computer restart, a lot of wild build path problems had appeared.
PS.: To solve these problems I closed the project in GGTS, used a grails clean in console, opened the project again (all the problems still were there), then I just gave a look into properties > Java Build Path and all problems have gone. These steps makes no sense for me.

Like others I would not recommend Eclipse. All variants(sts,ggts,vanilla eclipse+plugins) are unstable at least on Juno, IMHO.
I personally use emacs, but like #James, I would suggest IntelliJ:
stable as in no strange internal errors pop up while doing Grails coding, no project corruptions.
better completion, especially dynamic methods

Can Galileo work with workspaces/projects created in Helios?

My desktop has Helios (3.6.1). My workspace and the projects under it were created using Helios.
My laptop has Galileo (3.5.2). I tried to open a copy of a project that was created through Helios and it opened fine.
But then, when I tried to change one of the Java Libraries via Configure Build Path, I received Access Denied error:
At first, I thought it was a Windows XP permissions problem, but after investigating this further, I ruled out this possibility. I have also been able to modify that .classpath file using Notepad, so clearly this isn't an ACL problem.
Therefore, I am now suspecting that there is an incompatibility problem between Galileo (3.5.2) and Helios (3.6.1).
Can you confirm this?
If there shouldn't be a compatibility issue between the two, what could I possibly doing wrong?

The solution at this post - http://blog.ryanrampersad.com/2010/03/03/setting-build-path-has-encountered-a-problem-in-eclipse - may help you!
Summary:
"The windows hidden attribute is set on the .classpath file. Removing this attribute fixes the error. After going into the workspace and project directory, remove the hidden attribute."

Unfortunately, I celebrated too early. While Saket's tip allowed getting rid of the build path error, numerous other problems emerged, which forced me to upgrade from 3.5.6 to 3.6.2.
I then discovered the following in Eclipse's Release Notes:
Note: Copying your workspace is recommended because, after you've
upgraded your workspace, you won't be able to use it again with an
older version of Eclipse. If you ever want to go "back in time" to
an earlier release, you will need that backup.
Therefore, the short answer to my question is simply: No!

Error with Restlet sample project

I downloaded the sample Restlet project and opened it in Eclipse. I instantly get this error:
Errors occurred during the build.
Errors running builder 'Google WebApp Project Validator' on project 'org.restlet.example.serialization.gae-gwt'.
java.lang.NullPointerException
What am I doing wrong?

I had this same error with my own project. In the Eclipse Project Explorer I right-clicked the project and chose Refresh. That cleared up the error for me.

This is a temporary, but repeatable solution someone on my team found...
Close project
Close Eclipse
Open Eclipse
Open project

I continually had this problem in combination with git. My git repository was in my eclipse workspace ( even though eclipse warns you not to do this ). Deleting the old repository, and creating a new git repository outside of the eclipse workspace, then cloning a fresh copy of my gwt project solved this problem for me. Hope this helps.

I'm also experiencing this error, but thanks to git comparing .classpath I noticed that I had removed a couple of variables from the "Configure Variables" list, but not from the Java Build Path. Once I removed it from the second list, the error was gone.

I got this error when I was using a workspace that was on an NFS and I had the same workspace open on two different vnc sessions. I closed out Eclipse on one vnc session and then restarted eclipse on the other. Then I went to the java build path and editted the gwt sdk and had it use the gwt sdk it was already pointed to and it stopped giving me that error. I didn't actually change the gwt sdk, just went through the motions of doing so. Hope this helps.

The problem was miss configuration of JRE, I just did the following:
Go to Build path configuration, select add Library, JRE System Library, select your JRE.
And there you go...

For me this error seemed to occur after a compile had failed due to lack of memory and eclipse had been restarted. However, after increasing memory (in the eclipse.ini) the problem still persisted. None of the above solutions worked for me.
The bizarre solution I found: our project here uses GWT 2.4, so I switched to 2.5 (which comes with the plugin - window>preferences>google>Web Tookit), re-compiled, switched back to 2.4 and, hey presto, it worked again!
(Another hour of my life I'll never get back!)